Guys, I have to share with you a bit of what I've come up with :)
I have decided that they can make a recipes only if they have ingredients on hand and furthermore, I will be playing with the First Snow mod from SimCookie (you can google it since I cannot post links yet) and when winter comes - every 15 days, let's say - all of the plants go to family inventory until it's over. If they had enough money to build a greenhouse, some plants can stay there (will decide which ones soon, but trees are out), and when it's over, out of the inventory they go again!
Off I go to dl some wintery clothes :)